Analysis of oral self-administration patterns of drugs in capsule or solution preparation form by primates will be continued. Examination of specific environmental once pharmacological factors identified as relevant to generation, maintenance or elimination of self-administration will be pursued as will evaluation of measures which seem to provide sensitive indicants of drugs effects. AIA-sedative hypnotic and cyclic nucleotide-stimulant drug interactions which have been found to alter operant behavior patterns in rodents will be further examined in primates. The overall purpose of the investigations will be to further evaluate technical or procedural approaches and behavioral models which provide the opportunity to examine closer approximations of human drug taking patterns in controlled laboratory investigations with non-human subjects. Examples of analogs to be evaluated include (1) drug capsule self-administration itself and differences in relative reinforcing effectiveness of drugs administered via this, compared to other routes; (2) drug preference, and preference changes, as a function of environmental and pharmacological factors in terms of clinical phenomenon such as "compliance", "misuse", and "preparatory" use of behaviorally active drugs.